As we come on the air, president Obama announces that the U.S. Is in action in Iraq again tonight. He addressed the country's humanitarian catastrophe and what it would take to trigger military air strikes. To stop the advance honor bill, I directed our military to take targeted strikes against terrorist convoys should they move toward the city. We intend to stay vigilant and take action if the terrorist forces threaten our personnel or facilities anywhere in Iraq. Attacks by an Al qaeda-based terrorist group have forced the country into crisis. And now, tens of thousands are fleeing for their lives. Many of those families stranded without resources, atop of mountains in blistering heat. American forces began humanitarian air-drops there earlier today, delivering critical aid, much-needed food and water. As you just heard, president Obama authorizing targeted military strikes if those terrorists continue their advance towards Iraq's largest northern city. Stay with ABC news for all the latest on this developing story. And "Gma" will have a full report in the morning.

This transcript has been automatically generated and may not be 100% accurate.

U.S. contemplates humanitarian air drops over Iraq as humanitarian crisis worsens.

President Obama Authorizes 'Targeted' Air Strikes in Iraq

President said he'll call in air strikes against ISIS to protect American interests if necessary.

What Is The White House Doing To Address The Humanitarian Crisis In Iraq?

White House declines to say whether President Obama is weighing airstrikes or airdrops.

The Dramatic Gains ISIS Has Made in Iraq

Islamic militants have isolated thousands of Kurds in northern Iraq.

Obama Authorizes Air Strikes, Aid Mission in Iraq

The US is going back to Iraq to help stranded Kurds against ISIS.

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